Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2009
Publication Date: 11/16/2009
Citation: Moreau, R.A., Lampi, A.M., Hicks, K.B. 2009. Fatty acid phytosterol, and polyamine conjugate profiles of edible oils extracted from corn germ, corn fiber, and corn kernels. 2009. Journal of the American Oil Chemists' Society 86:p. 1209-1214.
Interpretive Summary: All commercial corn oil is obtained by extracting corn germ (embryos, obtained mostly from corn wet mills) with hexane and it is then refined via conventional alkali refining, bleaching and deodorization. In recent years processes have been reported and patented to produce corn fiber oil by extracting corn fiber with hexane and to produce corn kernel oil by extracting ground corn with ethanol. It is believed that both these oils may be commercially valuable since they contain much higher levels of health-promoting components such as phytosterols and carotenoids than does conventional corn oil. Because of the interest in all three corn oils, this study was designed to compare the profiles of fatty acids, phytosterols, and polyamine conjugates (compounds recently identified and found to occur at levels of about 1% in ethanol extracted corn kernel oil). The study confirmed that the fatty acid composition of all three oils was similar, with linolenic acid being the predominant fatty acid. The levels of cholesterol-lowering phytosterols were twofold and tenfold higher in corn kernel oil and corn fiber oil, compared to corn germ oil. Finally, polyamine conjugates were only detected in ethanol extracted corn kernel oil and conventional refining, bleaching and deodorization effected removed all of them from the corn kernel oil. The effective removal of polyamine conjugates by conventional oil refining is important because the safety of these compounds is unknown. This information will be useful to corn refiners both large and small, who are seeking to produce high quality, health promoting edible oils.
Technical Abstract: This study compared the profiles of fatty acids, phytosterols, and polyamine conjugates in “traditional” commercial corn oil extracted from corn germ and in two “new generation corn oils,” hexane extracted corn fiber oil and ethanol extracted corn kernel oil. The fatty acid compositions of all three corn oils were very similar and were unaffected by degumming, refining, bleaching, and deodorization. The levels of total phytosterols in crude corn fiber oil were about tenfold higher than those in commercial corn oil and their levels in crude corn kernel oil was more than twofold higher than conventional corn oil. When corn kernel oil was subjected to conventional degumming, refining, bleaching and deodorization, about half of the phytosterols were removed, whereas when corn fiber oil was subjected to a gentle form of degumming, refining, bleaching, and deodorization, only about 10% of the phytosterols were removed. Finally, when the levels of polyamine conjugates were examined in these corn oils, they were only detected in the ethanol-extracted, crude corn kernel oil, confirming earlier reports that they were not extracted by hexane, and providing new information that they could be removed from ethanol extracted corn kernel oil by conventional degumming, refining, bleaching and deodorizing.